In a condition monitoring system of a wind turbine, a number of parameters relating to the wind turbine are normally measured. Some of these parameters may relate to the health of one or more components of the wind turbine, such as a gear system, part of a gear system, a bearing, a generator, a drive shaft, etc. These parameters may include temperature, load, stress or strain of a component. Measuring and analysing such parameters allow an operator to detect when a component reaches a state where it is likely to break down.
When one of these parameters exceeds a certain value, an alarm is triggered and a service inspection is scheduled to inspect the component. The values, which trigger the alarm if exceeded, are predefined alarm levels of the component. Depending on the alarm level, the inspection is scheduled within a certain time so that the inspected component can be repaired or replaced before it actually fails.
Hence, it is crucial that the alarm levels are defined in such a way that they accurately reflect when the components are expected to fail. If the alarm levels are defined too high, the alarm may only be triggered when the component is about to fail very soon. Hence, the inspection may not be scheduled in time before the component fails, causing the wind turbine to be shut down. Breaking down or failure of the component before the scheduled inspection or maintenance may result in loss of power production, and hence income/profit, during the period between the component break down and the scheduled maintenance. The breaking down of the component before the scheduled maintenance may also require an unscheduled maintenance to be made, resulting in extra cost. If the alarm levels are defined too low, the alarm may be triggered too early which results in unnecessary inspection. This would also result in extra cost. Both of these situations result in increase in maintenance cost, and hence, increase in cost of energy.
In most systems, the alarm levels are predefined based on historical data from other similar components. Once the alarm levels for the components in the wind turbines are defined, they are fixed for the lifetime of the turbine. However, the same type of wind turbine may operate in different areas in the world with different climate. In addition, the characteristics and performance of different wind turbines having the same operating platform may also change due to other factors such as operation time, different components from different suppliers, etc. Thus, the initial alarm levels defined for the components in the wind turbine may not reflect the actual health of the respective components throughout the lifetime of the wind turbine.
Therefore, it is desirable to have a more accurate way of defining and adjusting the alarm levels of the components in a wind turbine.